diff --git a/src/common/compat_pthreads.c b/src/common/compat_pthreads.c
index e1d4b0e79b..f4a6cad154 100644
--- a/src/common/compat_pthreads.c
+++ b/src/common/compat_pthreads.c
@@ -3,6 +3,8 @@
  * Copyright (c) 2007-2015, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+#define _GNU_SOURCE
+
 #include "orconfig.h"
 #include <pthread.h>
 #include <signal.h>
diff --git a/src/common/compat_threads.c b/src/common/compat_threads.c
index 3b79292cdb..ba21c951fa 100644
--- a/src/common/compat_threads.c
+++ b/src/common/compat_threads.c
@@ -6,7 +6,6 @@
 #define _GNU_SOURCE
 
 #include "orconfig.h"
-#define _GNU_SOURCE
 #include <stdlib.h>
 #include "compat.h"
 #include "compat_threads.h"